Probability Definition and 1000 Threads

  1. murshid_islam

    Probability of Two Consecutive Same-Value Cards in a Shuffled Deck

    Not really a homework question. I was reading a book on card tricks and it said that it's almost certain that in a shuffled deck of cards, there will be at least two consecutive cards of the same value. I just wanted to know the actual probability of that. So, here's my question: in a standard...
  2. Samama Fahim

    Finding Probability of Two-Identical-Particle System in a Given State

    Problem: A system contains two identical spinless particles. The one particle states are spanned by an orthonormal system ##|\phi_k>##. Suppose that particle states are ##|\phi_i>## and ##|\phi_j>## (##i \neq j##). (a) Find the probability of finding the particle in the state ##|\xi>## and...
  3. WMDhamnekar

    MHB Probability of misprints on each page

    Hi, Each page of a book contains N symbols, possibly misprints. The book contains n =500 pages and r =50 misprints. Show that (a) the probability that pages number 1, 2, . . . , n contain, respectively , $r_1, r_2 , . . . , r_n $ misprints equals $$\frac{\binom{N}{r_1}\binom{N}{r_2}. ...
  4. T

    B Probability of eating one egg with salmonella

    ln Will Kurt's Kurt's book "Bayesian Statistics The Fun Way" he gives a problem at the end of a chapter " Raw eggs have a 1/20,000 probability of having salmonella. If you eat two raw eggs what is the probability that you ate a raw egg with salmonella." The online answer he gives: "For this...
  5. guyvsdcsniper

    Probability of electron in hydrogen nucleus for 1s and 2s wave-functions

    For this problem, Is it as simple as using the probability density function, P = Ψ2 and plugging in the radius value given to me? So essentially I am just squaring the wave function and plugging in?
  6. chwala

    Determine the probability of ##P(x>4)##

    Find the solution here; Ok my interest is on part (b) and (c) only. Let's start with (b), My take is, $$\int_4^5 \dfrac{2}{75}x\,dx=\left.[\frac{x^2}{75}]\right|_4^5$$ $$=(0.33333333-0.21333333)+\frac{2}{15}×5$$ $$=0.12+0.6666666666=0.78666666$$ note that at ##f(x)##=##\dfrac{2}{15}##, the...
  7. D

    I Probability of Sum of 2 Random Ints Being Prime

    if I select two integers at random between 1 and 1,000, what is the probability that their sum will be prime?
  8. J

    The infinite limits of the probability transition matrix for Markov chain

    Consider a Markov chain with state space {1, 2, 3, 4} and transition matrix P given below: Now, I have already figured out the solutions for parts a,b and c. However, I don't know how to go about solving part d? I mean the question says we can't use higher powers of matrices to justify our...
  9. chwala

    Problem involving Probability density function

    I just want to be certain, i think the inequality indicated is not correct...ought to be less than. Kindly confirm...This is a textbook literature.
  10. L

    [Bayes' Theorem] Finding the probability of guessing correctly

    I calculated the probability of box 1/2/3 given white. P(Box 1 | white) = P(Box 1)*P(White | Box 1)/(P(Box 1)*P(White | Box 1) + P(Not Box 1)*P(White | Not Box 1)) = ((1/3)*(1/2)) / (((1/3)*(1/2) + (2/3)*(5/7) = 7/27 P(Box 2 | white) = P(Box 2)*P(White | Box 2)/(P(Box 2)*P(White | Box 2) +...
  11. chwala

    Find the probability of choosing exactly 4 red cards

    Find the question and solution here ( sorry its a bit blurred) ... given using the hypergeometric method...i wanted to understand what is the clear distinction between hypergeometric and binomial distribution? Could it be in in reference to no replacement and replacement...? My approach on this...
  12. C

    I Taking socks out of drawers, conditional probability

    Problem: In a dresser there are 3 drawers. In one drawer there are two black socks and one white sock, in the second drawer there are two white socks, and in the third drawer there is a black and white sock. Suppose I chose a drawer randomly ( meaning, in a uniform distribution ) and I took a...
  13. Yan Campo

    I Probability when measuring a local observable

    I have information that $$\rho_{ab}=\sum_{j}p_{j}\ket{\Psi_{j}^{ab}}\bra{\Psi_{j}^{ab}}$$ and $$Pr(o_{j}^{(a)}|\Psi_{ab})=Tr_{ab}(\ket{\Psi_{ab}}\bra{\Psi_{ab}}(\ket{o_{j}^{(a)}}\bra{o_{j}^{(a)}}\otimes \mathbb{I}_{2})) \text{.}$$ I started by representing the density operator for pure states...
  14. S

    Conditional probability of a test records this positive result

    My attempt: $$P(\text{B is positive}|\text{A is positive})=\frac{P(\text{B is positive} \cap \text{A is positive})}{P(\text{A is positive})}$$ $$=\frac{P(\text{B is positive})\times P(\text{A is positive})}{P(\text{A is positive})}$$ $$=P(\text{B is positive})$$ $$=0.01 \times 0.99 + 0.99 \times...
  15. K

    I Probability in a small interval is ##P. dx##

    Reif says " ... variable ##u## which can assume any value in the continuous range ##a_{1}<u<a_{2}##. To give a probability description of such a situation, one can focus attention on any infinitesimal range of the variable between ##u## and ##u+d u## and ask for the probability that the variable...
  16. Lapse

    I How to Combine These Two Probabilities?

    I am trying to determine the likelihood of a driver winning a race based on an associated rating as well as the team he drives for. The probability that Driver A beats Driver B = .8504 The probability that Team A beats Team B = .7576 How do I combine these two probabilities, where the outcome...
  17. F

    Prob/Stats Which Probability books are good for the first course?

    Please tell me some good books on Probability for first course.
  18. shivajikobardan

    Comp Sci What is the probability that there is a burglary given John and Mary calls?

    this is the question Here is a tutorial video but his steps are very confusing to me. I personally know bayes theorem and have already studied probability and got good marks in it(It may not be a metric for being quality in it given that it is nepal we are talking about.)...
  19. Buzz Bloom

    I An idea for calculating the probability that the Universe is flat

    References (1) https://www.physicsforums.com/threads/what-is-the-probability-that-the-universe-is-absolutely-flat.971984/ (2) https://www.physicsforums.com/threads/calculating-the-probability-that-the-universe-is-finite.1011826/ Suppose the Friedmann equation is used to analyze two models. (1)...
  20. P

    B Decision for conditional probability instead of intersection of events

    Hello, I have a question about the following sentence and would appreciate if someone could explain how to read out the conditional probability here. "Each microwave produced at factory A is defective with probability 0.05". I understand the sentence as the intersection ##P(Defect \cap...
  21. K

    Using Poisson random variables to calculate this probability

    I calculated the mean which is 78.4 And the Standard deviation is 5.6 I thought the answer would be (90^(-78.4)/78.4!)*e^-90 But looking back having a decimal factorial doesn't make sense I have the numerical answers for c)= 0.019226 and d)=0.022750 but I my solution was wrong. Any help on...
  22. Buzz Bloom

    I Calculating the probability that the Universe is finite

    Reference https://www.cosmos.esa.int/documents/387566/387653/Planck_2018_results_L06.pdf I note that the use of Gaussian probabilities is mentioned many times in the reference. However in many discussions via posts in many threads, there seems to be a consensus that the distribution is...
  23. karush

    MHB Pb.20 What is the probability that Hiroko....will be chosen

    The 35 member History Club is meeting to choose a student government representative. \item The members decide that the representative, who will be chosen at random, CANNOT be any of the 3 officers of the club. What is the probability that Hiroko, who is a member of the club but NOT an officer...
  24. A

    A Solving an Integral involving a probability density function

    In an article written by Richard Rollleigh, published in 2010 entitled The Double Slit Experiment and Quantum Mechanics, he argues as follows: "For something to be predictable, it must be a consistent measurement result. The positions at which individual particles land on the screen are not...
  25. Grinkle

    B Can probability waves be "focused"?

    I really cannot ask this question well. I can only hope its not simply a waste of the readers time. I won't finish every sentance with "maybe I'm wrong", just assume its in my mind every time I hit the period key. An electron on a screen leaves a pixel spot, this pixel spot is a measurement...
  26. Mr_Allod

    Probability of finding a pion in a small volume of pionic hydrogen

    Hello, I am trying to figure out the right way to approach this. First of all, other than the different Bohr radius value, does the change to a negative pion make any other difference to calculating the probability? Also what would be the correct way to apply the "small volume"? What I'm...
  27. A

    I The probability density function for the double-slit experiment

    I am desperate. I've scoured the web for the formula for the probability density function for the interference pattern obtained in the double slit experiment with both slits open. So I want to know the probability density function and not the intensity function. I prefer not to have references...
  28. Fobi

    I Probability of 10 consecutive tails with 30 coin flips

    Hi, i was doing a programming exercise that asked me to simulate te flip of coins until it finds 10 consecutive tails. The program usually needs to flips like 6000/8000 coins before finding 10 tails consecutively, but suddenly i found 10 tails with only 30 coin flips, i think that what happened...
  29. L

    Find the probability of different scenarios

    Summary:: Bag A contains 1 white straw, 2 red straws and 2 green straws. Bag B contains 2 white straws, 2 red straws and 1 green straw. One straw is drawn at random from each bag. Find the probabilities that (a) the two straws drawn are of the same colour; (b) one straw is red and the other...
  30. K

    I Probability in statistical mechanics

    Suppose we've an isolated box having ##N## classical distinguishable particles in it, the box being hypothetically divided into two parts, left and right with both parts identical. Its said that the probability of having the configuration of ##n## particles in the left side is given as...
  31. J

    Can double masking increase efficacy by 126% against particles?

    Would the two masks together be 126% effective?
  32. M

    MHB Probability to get a chocolate snowman or a chocolate reindeer

    Hey! :giggle: $N\in \mathbb{N}$ christmas presents will be distributed. In every gift there is additional either a chocolate snowman or a chocolate reindeer. It will be independent of each other and with the same probability of giving out gifts with a chocolate snowman or chocolate reindeer...
  33. D

    Probability problem -- The joint PDF of X and Y is uniform on this rectangle....

    we haven't learned howw to do parts d-f yest. could you please give me a hand? (a) $$E(X)=E(Y)=\int_0^3\int_0^3\frac{1}{9}dxdy=\frac{3}{2}$$ (b)its typoe suppoesed to be W=Y-2 $$E(Z)=E(X-2)=E(X)-E(2)=-\frac{1}{2}$$ $$E(W)=E(Y-2)=E(Y)-E(2)=-\frac{1}{2}$$ (c) i guess joint pdf from ##E(Z)## and...
  34. L

    MHB Where Did the Monte Carlo Simulation Go Wrong?

    Two numbers are bring chosen by random from the set {1,2,3,4,5}. If the sum of the two numbers is even, you win 100 dollars, otherwise you win nothing. In order to participate in the game, you pay $80. What is the expected value and variance of the profit after 17 games ? I solved this one...
  35. issue

    A complex probability question

    There is a box with 2324784 bullets. Balls are divided into 5 groop and there is a definition for each groop and how many balls and what is the probability of getting each groop. The game with the return of the balls List the probability and quantity groop 1 906192 0.389796213 groop 2 1006880...
  36. A

    B Calculating the coprime probability of two integers in a different way

    The probability that two randomly chosen integers to be coprimes is known to be equal to ## \prod_{2}^{\infty}(1-\frac{1}{p^2})=6/\pi^2## I tried to conceptualize the problem in the following way but got different results. Suppose that we pick up an integer at random which could be either prime...
  37. D

    The joint probability - two coins

    (a) The probability mass function of X and Y: $$p_{X,Y}(1,1)= \frac{1}{2}\cdot \frac{3}{4}=\frac{3}{8}$$ $$p_{X,Y}(1,0)=\frac{1}{2}\cdot \frac{1}{4}=\frac{1}{8}$$ $$p_{X,Y}(0,1)= \frac{1}{2}\cdot \frac{3}{4}=\frac{3}{8}$$ $$p_{X,Y}(0,0)= \frac{1}{2}\cdot \frac{1}{4}=\frac{1}{8}$$ or $$...
  38. A

    MHB Want to use probability algorithm for my web app

    I'm a freelance web developer and right now I'm stuck into a mathematical(probability) issue where I'm developing an answer filtering tool. This tool works as follows: 1) There are six questions that the user will be asked 2) Based on the answer of first question, my server will decide which...
  39. R

    MHB What Is the Probability of Drawing Specific Ball Colors from a Bag?

    Hi guys, I have a maths question about Probability, hope somebody can help me out, thank you very much. There are 5 red, 4 blue and 3 green balls in a bag. Two balls are taken from the bag, one after the other. If the first ball is not replaced, and it was not green. What is the probability...
  40. evceteri

    Neutron scattering probability distribution

    Hi, I'm reading Chapter 2-II of of Duderstadt & Hamilton's "Nuclear Reactor analysis". In the section "Differential scattering cross sections with upscattering" it is discussed the situation in which neutrons suffers elastic scattering collisions in a hydrogen gas at finite temperature T and the...
  41. hackedagainanda

    Intro Math Introductory Probability without Calculus

    Are there any good introductory texts aimed at students with only a working knowledge of High School Algebra? I currently have: Probability: An Introduction by Samuel Goldberg I do plan on eventually learning Calculus, but I would like to start learning probability sooner.
  42. M

    MHB How can we find probability space and events

    Hey! :giggle: Give a probability space and events $A$, $B$ and $C$ such that $P [C \mid A]>P [C \mid A \cup B]$.So we want that $$\frac{P[C\cap A]}{P[A]}>\frac{P[C\cap (A\cup B)]}{P[A\cup B]}=\frac{P[(C\cap A)\cup (C\cap B)]}{P[A\cup B]}$$ But how can we find these events ? :unsure:
  43. M

    MHB Probability that a randomly selected chicken has the genetic modification

    Hey! :giggle: In the case of the reproduction of the chicken of the breed Krueper, in some cases it can be that they are extremely short-legged, which has as a result that they already die in the egg. A group of researchers now considers that they have found two main genetic modifications...
  44. M

    MHB How can we calculate the probability?

    Hey! :giggle: The distribution of a random variable $X:\Omega\rightarrow \mathbb{R}$ is given by the probability function $p_X$ as follows: (i) Calculate the distribution function $F_X$ of $X$. (ii) Let $Y(\omega)=|X(\omega)|$ for all $\omega\in \Omega$. Determine $p_Y$. I have done the...
  45. M

    I Using a probability argument I got the sum. Can it be done directly?

    ##\sum\limits_{k=0}^{n-m} \frac{\binom{n-m}{k}}{\binom{n}{k}}\frac{m}{n-k}=1##. Can be derived from question. For ##n\ge m##, pick ##m## marbled out of a set size ##n## labeled from ##1## to ##n##, what is probability distribution of minimum of the number labels on the marbles? The terms is...
  46. M

    Probability of getting 5 consecutive heads before 2 consecutive tails

    Hi, I was just having a go at this question, and I suppose I have two sub-questions: 1. Does my approach look correct? 2. If my approach is correct, is there a better approach than what I have done? Original question: Suppose we are flipping a fair coin. What is the probability that we observe...
  47. chwala

    Solve the probability without replacement problem

    My interest is solely on question ##6.V## only. This is the question paper; This is my working to solution; I was able to use tree diagram in this question. This is the mark scheme: I would appreciate other ways of tackling the problem. Cheers! :cool:
  48. L

    I The Prisoner Paradox: Examining the Relativity of Probability in Everyday Life

    For example, If I have a constant probability of 50% to death per day (sorry for the macabre example but I find it good); Every day I wake up, I can say:"Today, at the end of the day, I have a probability of 0.5 to be live( or to be dead)!". Now, one can calculate the probability that after...
  49. chwala

    Solve the probability distribution and expectation problem

    This is the problem; Find my working to solution below; find mark scheme solution below; I seek any other approach ( shorter way of doing it) will be appreciated...
  50. J

    Calculating the Probability of Particles Traveling Through Different Size Pores

    Homework Statement:: Not homework, but I want to calculate the probability of different size spheres traveling through different size pores. Relevant Equations:: V=4/3πr^3 volume of sphere. Volume of 60nm diameter particle = 1.13x10^5 nm^3. Volume of 70nm particle = 1.8x10^5 nm^3 Hi all, this...
Back
Top